NEW YORK (REUTERS).- Experts at New York's Metropolitan Museum of Art have determined that a 1624 portrait previously attributed to a follower of the Spanish painter Velázquez was done by the master himself.

The museum said the portrait of King Philip IV, which went on display on Tuesday, is authentic, reversing a 1973 finding that it had been done by an assistant to Velázquez.

The experts reached their conclusion after removing paint and varnish that had had been added to the damaged canvas over the years, the museum said.

The Met had downgraded the picture, determining it was likely done by an assistant or follower studying under Velázquez in his workshop, the Met said, confirming a story first reported in the New York Times on Tuesday.

Quite large at 6.5 feet tall by more than 3 feet wide, the portrait of an 18-year-old king underwent a restoration a year ago in which curators, conservators and scholars became convinced it was authentic, in part by using X-ray technology.

"For the museum, how could it not be important? One of the greatest painters of Western tradition -- and a royal portrait to boot -- is vindicated," Keith Christiansen, the Met's chairman of European paintings, told the Times.

For decades Velazquez was the official portraitist of the Spanish royal family. Many of his works, such as the renowned "Las Meninas" (The Maids of Honor) in which the image of a much older Philip appears in the background as family patriarch, hang in Madrid's Prado museum.